Andrewsarchus is a genus of entelodonts. Entelodontidae is afamily, within the suborder of Cetancodontamorpha, within the order of Artiodactyla. While sheep are also artiodactylates, they are most closely related to cattle, goats, and antelope, and slightly more distantly related to deer and giraffes. Cetancondontamorpha contains not only entelodonts like Andrewsarchus, but also Cetacea- whales and dolphins- and hippopotamids, including living and extinct hippos.

So no. Their closest relatives are not sheep.

And what really gets my goat pun intended is that they said they were related to sheep because it's a weird thing to think about, when not only are there other slightly related animals that are weirder choices (giraffes, cows) their actual closest living relatives- whales- is the weirdest of all. It's like lying and saying you saw a parrot dance, when in reality you saw a zebra do the macarena.

Dingoes were similarly sized to male thylacines but were considerably larger than female thylacines on mainland Australia during the Holocene. Small size may have made female thylacines particularly susceptible to direct killing by dingoes and such killing could have driven thylacines to extinction. Due to their lower metabolic rate and convergent morphology, thylacines would have also been susceptible to resource competition with dingoes, but competition is generally thought to be a weaker extinction threat than predation. Our results provide support for the hypothesis that direct killing by larger dingoes contributed to the extinction of the thylacine on mainland Australia. However, attributing the extinction of the thylacine to just one cause is problematic because the arrival of dingoes coincided with another potential extinction driver, the intensification of the human economy.

Along with that Thylacines weren't suited for pressure, they had strong bites but can't handle stress.